A Bi-polar Current Source with High Short-term Stability for Tsinghua Tabletop Kibble Balance

TL;DR

This paper presents a high-stability, bi-polar digital-feedback current source designed specifically for Kibble balance experiments, utilizing commercially available components to achieve nanoradian stability essential for precise mass measurements.

Contribution

The paper introduces a novel two-stage, digitally controlled current source that is commercially feasible and offers high short-term stability for Kibble balance applications.

Findings

Achieves nA/A stability suitable for Kibble balance measurements

Uses only commercially available components and voltmeters

Demonstrates effective compensation of current fluctuations

Abstract

A high-precision current source, capable of supporting weighing measurements with a relative uncertainty at the $10^{-9}$ level, is essential for Kibble balance experiments. However, most current sources utilized in Kibble balances to date are homemade and not commercially available. In this paper, we introduce a digital-feedback, two-stage current source designed for the Tsinghua tabletop Kibble balance, relying solely on commercially available sources and voltmeters. A high-resolution, small-range current source is employed to digitally compensate for current output fluctuations from a large-range current source. Experimental tests show the proposal can offer an easy realization of a current source with nA/A stability to support Kibble balance measurements.